TKS. When you start appx .010 off the lands what start pressure do you generally input into the program to get best true results.
CAPE COVE
I usually start with a reloading manual recommendation for maximum... minus 0.6 gr powder charge. I've been using mostly Hornady data for the last few years when working up a new load. They seem to be overly conservative so I feel safe. I've never had an "Uh oh" moment doing this. I like Sierra, too.
Then I change one thing at a time: powder, seating depth, start pressure.
If I am off the lands... any distance... I start with 3625 psi for jacketed bullets.
If I am jam, then I start with 2x3625 =7250 psi. I believe that this is overly cautious but I haven't had an issue with pressure when I use this number.
Now, if I am case neck trimming I get a Base Line load... say, manual maximum minus 0.4 gr, .0010" off jam, 3625 psi start pressure... I then input a reduction of 1,000 psi for start pressure and compare the model with actual range data. This process can be tedious because it's Trial-and-Error. A change in station temperature will cause fluctuations, too. I continue to make start pressure changes, maybe 500 psi steps reducing/increasing the step by half, up or down, until my QL model output matches my range velocity, within one SD.
This is pretty much how I "true" QL. I don't do it for every caliber that I have. I do it for my .222 Rem Bench Rest rifle, my 6.5 CM when I'm shooting beyond 880 yds (arbitrary distance selection), and my 24" .308.
Also, in many cases, I don't need to make any standing pressure changes. They are the micro adjustments available when needed. I look at standing pressure as a minor variable.
Let me know if you need anything else. Hope this is of some help. If anyone has a better way, please share
Best regards
